The present invention relates to a stabiliser for a vehicle frame.
Such a stabiliser has the purpose of preventing the superstructure of a vehicle from rolling relative to its substructure, e.g. when cornering and it is referred to in DE-A-3 730 338. When the vehicle tends to roll, the two shanks of the stabiliser twist and bend. The resulting difference in height between the ends of the respective shanks is accommodated by a rotary motion (torsion) in the bar extending between the shanks, which, owing to its inherent elastic characteristics, counteracts the twisting and hence also the rolling. Stabilisers of this kind have proven to have excellent stabilising characteristics, particularly in heavy-duty vehicles such as trucks, buses etc., but have a serious disadvantage in that the life of the shanks may, depending on their operating conditions, be significantly shorter than that of the torsion bar. This is very disadvantageous, since a shank fracture may have considerably more serious consequences than a torsion bar fracture.
The background to the problem is that these shanks are subject to large bending stresses when the vehicle rolls, because such rolling makes the wheel shaft swivel about a point and displace the shanks laterally in the region where they are connected to the wheel shaft. The shanks and the welded connections between them and the bar are also subject to tensile and bending stresses caused by vertical forces which occur when the vehicle rolls. If the shanks are to absorb lateral movements, they need a certain flexibility. If they are to have long life, they have also to be amply dimensioned. A conflict situation arises here in that the stronger the shanks, the less flexible they are. Manufacturers of known stabilisers of this type are therefore compelled in practice to use somewhat under-dimensioned shanks in order to provide sufficient flexibility. This results in the problem of the life of the shanks being generally shorter than that of the torsion bar.